[netflow-tools] softflowd & dd-wrt

Joe Courtney JCourtney at unitedmcgill.com
Fri Apr 18 00:19:13 EST 2008


Does anyone have softflowd running successfully on an open-source 
dd-wrt firmware router?  I am 99% done with getting it working, but 
I'm running into a problem "seeing" all the network traffic I wish to 
monitor.  It is probably an IPTables or routing /filtering issue or 
how I've configured the IPs of my interfaces, but I can't seem to 
wrap my head around the exact problem.  If I can figure this out, it 
is really going to be a nice way to send NetFlow data to a collector 
from a cheapo $50 router.

I was able to install the Optware package for softflowd on the router 
(DD-WRT v24 RC-7 (03/13/08) std).  I also installed tcpdump to make 
sure it wasn't an issue with softflowd (it isn't.)  The problem is 
I'm only seeing broadcasts on the interface I'm monitoring (no 
traffic).  (When setup on a full Linux box, I never had to do 
anything to the interface to monitor all the traffice.)  For some 
reason on the dd-wrt, there is some kind of filtering happening that 
is preventing softflowd and tcpdump from seeing all the traffic.

dd-wrt configuration:

[WAN] --- Port 0 --------- Vlan1 ------- Eth0
[Port1] --- Port 1 -------- Vlan0 -------- Eth0
[Port2-4] - Port2-4 ------ Vlan0 * Default Vlan for non-tagged traffic

So I have tried to use all the Ports for monitoring and many 
configurations of Vlans, but no luck.  I have also tried putting the 
interfaces in permisc mode with ifconfig, but no luck.  It seems the 
router is filtering all traffic.  The firewall and gatway settings 
are off, the thing should be able to see all the traffic.

ifconfig:
br0s are for the Wireless (eth1. WLAN), that doesn't come into play 
for this config.  Below I have added a second vlan, but no luck.

br0       Link encap:Ethernet  HWaddr 00:1A:70:FE:49:AE
           inet addr:192.168.0.11  Bcast:192.168.3.255  Mask:255.255.252.0
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:64919 errors:0 dropped:0 overruns:0 frame:0
           TX packets:29719 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:4611647 (4.3 MiB)  TX bytes:12926366 (12.3 MiB)

br0:0     Link encap:Ethernet  HWaddr 00:1A:70:FE:49:AE
           inet addr:169.254.255.1  Bcast:169.254.255.255  Mask:255.255.0.0
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

eth0      Link encap:Ethernet  HWaddr 00:1A:70:FE:49:AE
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:70842 errors:0 dropped:0 overruns:0 frame:0
           TX packets:99384 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:6515481 (6.2 MiB)  TX bytes:18729587 (17.8 MiB)
           Interrupt:4

eth1      Link encap:Ethernet  HWaddr 00:1A:70:FE:49:B0
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:0 errors:0 dropped:0 overruns:0 frame:1051593
           TX packets:56157 errors:2011 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:0 (0.0 B)  TX bytes:4376609 (4.1 MiB)
           Interrupt:2 Base address:0x5000

lo        Link encap:Local Loopback
           inet addr:127.0.0.1  Mask:255.0.0.0
           UP LOOPBACK RUNNING MULTICAST  MTU:16436  Metric:1
           RX packets:5896 errors:0 dropped:0 overruns:0 frame:0
           TX packets:5896 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:566715 (553.4 KiB)  TX bytes:566715 (553.4 KiB)

vlan0     Link encap:Ethernet  HWaddr 00:1A:70:FE:49:AE
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:60373 errors:0 dropped:0 overruns:0 frame:0
           TX packets:29694 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:4454776 (4.2 MiB)  TX bytes:7696374 (7.3 MiB)

vlan1     Link encap:Ethernet  HWaddr 00:1A:70:FE:49:AF
           inet addr:192.168.4.19  Bcast:192.168.4.23  Mask:255.255.255.248
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:392 errors:0 dropped:0 overruns:0 frame:0
           TX packets:9269 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:24430 (23.8 KiB)  TX bytes:428006 (417.9 KiB)

vlan2     Link encap:Ethernet  HWaddr 00:1A:70:FE:49:AE
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:10087 errors:0 dropped:0 overruns:0 frame:0
           TX packets:60451 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:765828 (747.8 KiB)  TX bytes:9838153 (9.3 MiB)



default IPTables:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
ACCEPT     0    --  anywhere             anywhere
logdrop    0    --  anywhere             anywhere            state INVALID
TCPMSS     tcp  --  anywhere             anywhere            tcp 
flags:SYN,RST/SYN tcpmss match 1461:65535 TCPMSS set 1460
lan2wan    0    --  anywhere             anywhere
ACCEPT     0    --  anywhere             anywhere            state 
RELATED,ESTABLISHED
ACCEPT     udp  --  anywhere             base-address.mcast.net/4 udp
TRIGGER    0    --  anywhere             anywhere            TRIGGER 
type:in match:0 relate:0
trigger_out  0    --  anywhere             anywhere
ACCEPT     0    --  anywhere             anywhere            state NEW

Chain logaccept (0 references)
target     prot opt source               destination
ACCEPT     0    --  anywhere             anywhere

Chain logdrop (1 references)
target     prot opt source               destination
DROP       0    --  anywhere             anywhere

Chain logreject (0 references)
target     prot opt source               destination
REJECT     tcp  --  anywhere             anywhere            tcp 
reject-with tcp-reset

Thanks for any info. or comments.



Joe Courtney

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